IEC 62319-1:2005

INTERNATIONAL IEC
STANDARD 62319-1
First edition
2005-02
Polymeric thermistors –
Directly heated positive step function
temperature coefficient –
Part 1:
Generic specification
Reference number
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INTERNATIONAL IEC
STANDARD 62319-1
First edition
2005-02
Polymeric thermistors –
Directly heated positive step function
temperature coefficient –
Part 1:
Generic specification
 IEC 2005  Copyright - all rights reserved
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mechanical, including photocopying and microfilm, without permission in writing from the publisher.
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V
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 62319-1  IEC:2005(E)
CONTENTS
FOREWORD.4

1 General .6
1.1 Scope.6
1.2 Normative references .6
2 Technical data.7
2.1 Units and symbols .7
2.2 Terms and definitions.7
2.3 Preferred values .10
2.4 Marking .11
3 Quality assessment procedures .11
3.1 General .11
3.2 Primary stage of manufacture .11
3.3 Subcontracting .12
3.4 Structurally similar components .12
3.5 Qualification approval procedures .12
3.6 Rework and repair .18
3.7 Release for delivery.18
3.8 Certified test records of released lots .19
3.9 Delayed delivery.19
3.10 Alternative test methods .19
3.11 Manufacture outside the geographical limits of IECQ NSIs.19
3.12 Unchecked parameters .19
4 Test and measurement procedures .19
4.1 Standard conditions for testing.19
4.2 Drying and recovery.20
4.3 Visual inspection and check of dimensions.20
4.4 Zero power resistance .21
4.5 Insulation resistance (for insulated types only) .21
4.6 Voltage proof (for insulated types only) .22
4.7 Robustness of terminations (for leaded types only).22
4.8 Soldering.23
4.9 Mounting .23
4.10 Rapid change of temperature .24
4.11 Climatic sequence .24
4.12 Cycle life testing .25
4.13 Trip endurance .27
4.14 Trip current .28
4.15 Hold current .28
4.16 Residual current and power dissipation .29
4.17 Time-to-trip .29
4.18 Cold environmental electrical cycling.30
4.19 Thermal runaway.30

62319-1  IEC:2005(E) – 3 –
Annex A (normative) Fixed sample size test schedules for qualification approval.31
Annex B (normative) Vibration-, bump-, shock-, shear-, substrate bending test.32
B.1 Vibration .32
B.2 Bump .32
B.3 Shock.33
B.4 Shear (adhesion) test .33
B.5 Substrate bending test.33

Figure 1 – Test schedule flow chart.15
Figure 2 – Circuit for Trip endurance .28

Table 1 – Fixed sample size test schedule for qualification approval of Polymeric PTC
thermistors for current limitation, assessment level EZ.16
Table 2 – Quality conformance inspection for lot-by-lot inspection.17
Table 3 – Quality conformance inspection for periodic testing .18
Table 4 – Loading weight for wire terminations .22
Table 5 – Number of cycles.25

– 4 – 62319-1  IEC:2005(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POLYMERIC THERMISTORS –
DIRECTLY HEATED POSITIVE STEP FUNCTION
TEMPERATURE COEFFICIENT –
Part 1: Generic specification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62319-1 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
40/1505/FDIS 40/1534/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62319-1 © IEC:2005(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of March 2009 have been included in this copy.

– 6 – 62319-1  IEC:2005(E)
POLYMERIC THERMISTORS –
DIRECTLY HEATED POSITIVE STEP FUNCTION
TEMPERATURE COEFFICIENT –
Part 1: Generic specification
1 General
1.1 Scope
This part of IEC 62319 prescribes terms and methods of test for polymeric positive
temperature coefficient thermistors, insulated and non-insulated types, typically intended for
use in current limiting and overcurrent protection applications.
It establishes standard terms, inspection procedures and methods of test for use in detail
specifications for Qualification Approval and for Quality Assessment Systems for electronic
components.
1.2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60027-1: Letter symbols to be used in electrical technology – Part 1: General
IEC 60050: International Electrotechnical Vocabulary
IEC 60068-1: Environmental testing – Part 1: General and guidance
IEC 60068-2-6: Environmental testing – Part 2: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-14: Environmental testing – Part 2: Tests – Test N: Change of temperature
IEC 60068-2-20: Environmental testing – Part 2: Tests – Test T: Soldering
IEC 60068-2-21: Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
IEC 60068-2-27: Environmental testing – Part 2: Tests – Test Ea and guidance: Shock
IEC 60068-2-29: Environmental testing – Part 2: Tests – Test Eb and guidance: Bump
IEC 60068-2-45: Environmental testing – Part 2: Tests – Test XA and guidance: Immersion in
cleaning solvents
IEC 60294: Measurement of the dimensions of a cylindrical component having two axial
terminations
IEC 60410: Sampling plans and procedures for inspection by attributes.

62319-1  IEC:2005(E) – 7 –
IEC 60617-DB: 2001 Graphical symbols for diagrams
IECQ 001003: IEC Quality Assessment System for Electronic Components – Guidance
documents
IECQ 001002-3: IEC Quality Assessment System for Electronic Components – Rules of
Procedure – Part 3: Approval procedures
ISO 1000: SI units and recommendations for the use of their multiples and of certain other
units
2 Technical data
2.1 Units and symbols
Units, graphical symbols, letter symbols and terminology shall, whenever possible, be taken
from the following documents:
IEC 60027
IEC 60050
IEC 60617
ISO 1000
The following subclauses contain additional terminology applicable to thermistors.
Where further items are required they shall be derived in accordance with the principles of the
documents listed above.
2.2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.2.1
thermistor
thermally sensitive semiconducting resistor whose primary function is to exhibit an important
change in electrical resistance with a change in body temperature
2.2.2
positive temperature coefficient thermistor
thermistor in which the resistance increases with increasing temperature throughout the
useful part of its characteristic. The PTC thermistors covered in this specification typically
exhibit a very sharp increase in resistance over a narrow temperature range
2.2.3
directly heated positive temperature coefficient thermistor
thermistor in which the change in temperature is obtained either by the flow of current through
the thermo-sensitive element, or by a change in ambient temperature, or by a combination of
both of these means
___________
“DB” refers to the IEC on-line database.

– 8 – 62319-1  IEC:2005(E)
2.2.4
zero power resistance
R
T
value of the resistance of a PTC thermistor, at a given temperature, under such conditions
that the change in resistance due to the internal generation of heat is negligible with respect
to the total error of measurement
NOTE Any resistance value of a PTC thermistor is dependent on the value and the mode of the applied voltage
(AC or DC).
2.2.5
nominal zero power resistance
R
n
zero power resistance used as a reference value for which the following conditions should be
given in the detail specification:
a) reference temperature, preferably 25 °C
b) applied voltage (DC or AC)
2.2.6
resistance/temperature characteristics
relationship between the zero power resistance of a thermistor and the temperature of the
thermosensitive element when measured under specified reference conditions
2.2.7
upper category temperature
UCT
maximum ambient operating temperature of the thermistor
2.2.8
lower category temperature
LCT
minimum ambient operating temperature of the thermistor
2.2.9
trip event
event of rapid increasing resistance of the thermistor in response to an overcurrent surge
2.2.10
minimum initial resistance
R
min
minimum resistance of the thermistor
2.2.11
maximum initial resistance
R
max
maximum resistance of the thermistor before it’s initial trip event
2.2.12
maximum resistance 1 h after tripping
R
1max
for leaded thermistors the maximum resistance of the thermistor 1 h after it’s first trip event;
for surface mount thermistors, the maximum resistance of the thermistor 1 h after reflow
2.2.13
maximum voltage
U
max
maximum AC or DC voltage which may be applied to the thermistor

62319-1  IEC:2005(E) – 9 –
2.2.14
operating temperature range at maximum voltage
range of ambient temperatures at which the thermistor can operate at the maximum voltage
2.2.15
isolation voltage (applicable only to insulated thermistors)
maximum peak voltage which may be applied under continuous operating conditions between
any of the thermistor terminations and any conducting surface
2.2.16
maximum current
I
max
value of current for the operating temperature range, which should not be exceeded
2.2.17
residual current
I
res
value of current in the tripped thermistor at a specified ambient temperature (preferably
25 °C) under steady state conditions; the applied voltage is the maximum voltage unless
otherwise specified
2.2.18
trip current
I
t
lowest current which will cause the thermistor to trip to its high resistance state at a specified
temperature (preferably 25 °C) and within a time specified in the detail specification
2.2.19
hold current
I
h
the maximum current at specified ambient temperature, preferably 25 °C, which will not cause
the trip event
2.2.20
fault current
I
fault
current used when measuring time to trip
2.2.21
power dissipation
P
d
product of the current flowing through a device and the voltage across it, under steady state
conditions; the applied voltage is the maximum voltage unless otherwise specified
2.2.22
time-to-trip
t
trip
under specified ambient conditions, starting from the time the fault current (I ) is applied,
fault
the time-to-trip is the time required for a device to switch into the tripped state
2.2.23
insulated thermistors
thermistors capable of meeting the requirements of the insulation resistance and voltage proof
tests when specified in the test schedule

– 10 – 62319-1 © IEC:2005(E)
2.3 Preferred values
2.3.1 Climatic categories
The thermistors covered by this specification are classified into climatic categories according
to the general rules given in the annex to IEC 60068-1. The detail specification prescribes the
appropriate category.
2.3.2
Void
2.3.3 Shock test severities
Test severities given in detail specifications shall preferably be the following:
Test Ea (IEC 60068-2-27)
Pulse shape: Half sine
Acceleration: 500 m/s
Pulse duration: 11 ms.
Severity: 3 successive shocks in each axis direction per specimen. Separate specimens to be
used for each axis (6 shocks total per specimen).
NOTE The shock and bump tests are normally specified as alternatives.
2.3.4 Vibration severities
Test severities given in the detail specifications shall preferably be selected from the
following:
Test Fc (IEC 60068-2-6)
Frequency range: 10 Hz to 55 Hz or 10 Hz to 500 Hz
Amplitude: 0,75 mm or 100 m/s (whichever is the less severe)
Sweep endurance: Total duration 6 h.
Thermistors shall be mounted by their normal means, in such a manner that there shall be no
parasitic vibration. During vibration testing there shall be no interruption in electrical continuity
greater than 0,5 ms.
62319-1  IEC:2005(E) – 11 –
2.4 Marking
2.4.1 General
The following shall be clearly marked on the thermistor in the following order of precedence
as space permits:
a) values of the primary characteristics appropriate to the application of the thermistor to be
specified in the detail specification. When these values are coded (including colour
coding), details shall be given in the detail specification or type designation;
b) manufacturer's name and/or trade mark;
c) date of manufacture or date code;
d) the number of the detail specification and style.
The package containing the thermistors shall be clearly marked with all the information listed
above.
Any additional marking shall be so applied that no confusion can arise.
3 Quality assessment procedures
3.1 General
When these documents are being used for the purposes of a full quality assessment system
such as the IEC Quality Assessment System for Electronic Components (IECQ), compliance
with 3.5 is required.
When these documents are used outside such quality assessment systems for purposes such
as design proving or type testing, the procedures and requirements of 3.5.1 and 3.5.3 b) may
be used, but if used, the test and parts of tests shall be applied in the order given in the test
schedule.
Before thermistors can be qualified according to the procedures of this clause, the
manufacturer shall obtain the approval of his organisation in accordance with the provisions of
IECQ 001002-3.
The method for the approval of thermistors of assessed quality given in 3.5 is qualification
approval according to the provisions of Clause 3 of IECQ 001002-3.
3.1.1 Applicability of qualification approval
Qualification approval is appropriate for a standard range of thermistors manufactured to
similar design and production processes and conforming to a published detail specification.
The programme of tests defined in the detail specification for the appropriate assessment and
performance levels applies directly to the subfamily of thermistors to be qualified, as
prescribed in 3.5 and the relevant blank detail specification.
3.2 Primary stage of manufacture
The primary stage of manufacture is defined as the initial compounding process of the
ingredients.
– 12 – 62319-1  IEC:2005(E)
3.3 Subcontracting
If subcontracting of the primary stage of manufacture and/or subsequent stages is employed it
shall be in accordance with 4.2.2 of IECQ 001002-3.
The blank detail specification may restrict subcontracting in accordance with 4.2.2.2 of
IECQ 001002-3.
3.4 Structurally similar components
Thermistors may be grouped as structurally similar for the purpose of forming inspection lots
provided the following requirements are met:
a) they shall be produced by one manufacturer on one site using essentially the same
design, materials, processes and methods;
b) the sample taken shall be determined from the total lot size of the grouped devices;
c) structurally similar devices should preferably be included in one detail specification but the
details of all claims to structural similarity shall be declared in the qualification approval
test reports.
3.4.1 For electrical tests, devices having the same electrical characteristics may be
grouped provided the element determining the characteristic is similar for all the devices
concerned.
3.4.2 For environmental tests, devices having the same type of insulation, basic internal
structure and finishing processes may be grouped.
3.4.3 For visual inspection (except marking), devices may be grouped if they have been
made on the same production line, have the same dimensions, type of insulation and external
finish.
This grouping may also be used for robustness of terminations and soldering tests where it is
convenient to group devices with different internal structures.
3.4.4 For endurance tests, thermistors may be grouped if they have been made on the
same production line using the same design and differing only in electrical characteristics. If it
can be shown that one type from the group is more heavily stressed than the others then tests
on this type may be accepted for the remaining members of the group.
3.5 Qualification approval procedures
3.5.1 Eligibility for qualification approval
The manufacturer shall comply with 3.1.1 of IECQ 001002-3.
3.5.2 Application of qualification approval
The manufacturer shall comply with 3.1.3 of IECQ 001002-3.
3.5.3 Test procedures for qualification approval
One of the two following procedures shall be followed:
a) the manufacturer shall produce test evidence of conformance to the specification
requirements on three inspection lots for lot-by-lot inspection taken in as short a time as
possible and one lot for periodic inspection. No major changes in the manufacturing
process shall be made in the period during which the inspection lots are taken.

62319-1  IEC:2005(E) – 13 –
Samples shall be taken from the lots in accordance with IEC 60410. Normal inspection
shall be used, but when the sample size would give acceptance on zero non-
conformances, additional specimens shall be taken to meet the sample size requirements
to give acceptance on one non-conforming item.
b) the manufacturer shall produce test evidence to show conformance to the specification
requirements on the fixed sample size test schedule given in 3.5.4.
The specimens taken to form the sample shall be selected at random from current
production or as agreed with the National Supervising Inspectorate (NSI).
For the two procedures, the same sample sizes shall be of comparable order. The test
conditions and requirements shall be the same.
3.5.4 Qualification approval on the basis of the fixed sample size procedure
The fixed sample size test schedule for qualification approval given hereinafter is appropriate
to the intended application of the thermistor that is to be approved. The schedule provides
information on the test grouping and sampling and acceptance criteria. The conditions of test
and the end of test requirements shall be identical to those specified in the related blank
detail specification for the lot-by-lot and periodic tests.
Tests
The complete series of tests specified in Table 1 are required for the approval of thermistors
covered by the detail specification. The tests of each group shall be carried out in the order
given.
The whole sample shall be subjected to the tests of Group 0 and then divided for the other
groups.
Non-conforming specimens during the tests of Group 0 shall not be used for the other groups.
“One non-conforming item” is counted when a thermistor has not satisfied the whole or a part
of the tests of a group.
The approval is granted when the number of non-conformances does not exceed the specified
number of permissible non-conforming items for each group or subgroup and the total number
of permissible non conformances.
The following list applies to the test schedule detailed in Table 1:
a) clause number references are to clauses in this specification;
b) 1) where the test schedule of a blank detail specification omits a test, that test may be
omitted from the fixed sample size schedule in this specification;
2) where additional tests are specified in the detail specification, that test shall be included
in the fixed sample schedule, either by its addition to an existing group or, by the addition
of another group. In the former case there shall be no change in the number of specimens
to be tested or in the acceptance criteria. In the latter case the number of specimens to be
tested and the acceptance criteria shall be comparable to those already specified;
c) in this table:
n is the sample size;
c is the group acceptance criteria (permitted number of defectives per group);
D indicates a destructive test;
ND indicates a non-destructive test;

– 14 – 62319-1  IEC:2005(E)
d) the temperature at which the zero power resistance shall be measured is specified in the
detail specification. The temperature shall be stated, where required, in the test schedule;
e) data for conditions of test are defined in the detail specification;
f) the additional specimens are to permit substitution for incidents not attributable to the
manufacturer. The specimens may be used to replace non-conforming specimens which
occur as a result of a test in a group which is identified as being “destructive”. Where a
specimen is used for this purpose, it shall be subjected to those tests in the group to
which the non-conforming item had already been subjected, before proceeding with the
remaining tests in the group;
g) the specimens used for this group may, at the discretion of the manufacturer, be used for
any subsequent group which is identified as being “destructive”;
h) ten samples from Group 0 test samples have to be chosen, 5 having the lowest zero
power resistance of the samples shall be used for Group 1A, 5 having the highest zero
power resistance of the samples for Group 1B;
i) the soldering – solderability and soldering – resistance to soldering heat tests shall only
be applied where the thermistor has terminations which are appropriate for soldering;
j) where the terminations are stated to be suitable for printed wiring applications, the
appropriate test conditions in IEC 60068 shall apply;
k) the thermistors shall be mounted by their normal means;
l) the vibration, bump and shock tests are only conducted if required in the detail
specification.
62319-1  IEC:2005(E) – 15 –
Trip Residual Voltage
Group 0 current current and proof
5 pcs
Power
dissipation
80 pcs
Group 1
(+5 spare)
Destructive
Hold
5 pcs
current
(Power
dissipation
at I
hold
5 pcs Solder Robustness
heat
Group 2
Destructive
Tests
5 pcs Vibration Bump (or)
shock
Visual
Marking
Group 3 10 pcs Rapid temp.
Destructive
change
Zero
Group 4 10 pcs Detail
power
Non
Dimens.
resistance
Destructive
Group 5 10 pcs Cycle life
Destructive
Group 6 10 pcs Trip
Destructive
endurance
Group 7 10 pcs Climatic
Destructive
sequence
Cold envir.
Group 8 10 pcs
electr.
Destructive
Non
cycling
Destructive
Group 9 10 pcs Thermal
Destructive
runaway
Group 10 10 pcs Solderability
Destructive
IEC  218/05
Vibration, bump and shock tests are not required but may be performed to obtain
supplementary information.
Figure 1 – Test schedule flow chart

– 16 – 62319-1  IEC:2005(E)
Table 1 – Fixed sample size test schedule for qualification approval of polymeric PTC
thermistors for current limitation, assessment level EZ
Group Test Clause/subclause D or Number of Permissible
No of this standard ND specimens number of non-
conforming
items
n c
0 Visual examination 4.3.1 ND 80 + 5 0
Marking 4.3.2
Zero power resistance 4.4
1  D
1A Trip current 4.14 5 0
Residual current and power 4.16
dissipation
Voltage proof 4.6
1B Hold current 4.15 5 0
Power dissipation at I hold
Voltage proof 4.6
2A Resistance to soldering heat 4.8.2 D 5 0
Robustness of terminations 4.7

2B Vibration B.1 D 5 0
Bump (or) shock B.2 (or) B.3
3 Rapid change of temperature 4.10 D 10 0
4 Detail dimensions 4.3.3 ND 10 0
5 Cycle life 4.12 D 10 0
6 Trip endurance 4.13 D 10 0
7 Climatic sequence 4.11 D 10 0
8 Cold environmental electrical 4.18 D 10 0
cycling
9 Thermal runaway 4.19 D 10 0
10 Solderability 4.8.1 D 10 0
62319-1 © IEC:2005(E) – 17 –
3.5.5 Granting of qualification approval
Qualification approval shall be granted when the procedures in accordance with 3.1.4 of
IECQ 001002-3 have been completed satisfactorily.
3.5.6 Maintenance of qualification approval
Qualification approval shall be maintained by regular demonstration of compliance with the
requirements for quality conformance (see 3.5.7).
3.5.7 Quality conformance inspection
3.5.7.1 The blank detail specifications associated with this specification shall prescribe the
test schedule for quality conformance inspection. This schedule shall also specify the
grouping, sampling and periodicity for the lot-by-lot and periodic inspection (see Table 2 and
Table 3).
Sampling plans and inspection levels shall be selected from those given in IEC 60410.
If required, more than one schedule may be specified.
An inspection lot shall consist of thermistors of the same style. It should be representative of
those extremes of resistance and switching temperature range produced during the inspection
period.
The sample for Groups C and D shall be collected over the last 13 weeks of the inspection
procedure.
3.5.7.2 Assessment level
The assessment level given in the blank detail specification shall be in accordance with
Table 2 and Table 3.
Table 2 – Quality conformance inspection for lot-by-lot inspection

Inspection  Assessment level
d
subgroup EZ
a a a
IL n c
b
A0 100 %
c
A1 S-4 0
c
A2 S-3 0
c
B1 S-2 0
c
B2 S-2 0
a
IL is the inspection level.
n is the sample size
c is the permissible number of non-conforming items
b
100 % testing shall be followed by re-inspection by sampling in order to monitor outgoing quality level by non-
-6
conforming items per million (10 ). The sampling level shall be established by the manufacturer. For the
-6
calculation of 10 values parametric failures shall be counted as a non-conforming item. In case one or more non-
conforming items occur in a sample, this lot shall be rejected.
c
Number to be tested: sample size as directly allocated to the code letter for IL in Table IIA of IEC 60410 (single
sampling plan for normal inspection)
d
The content of the inspection subgroups is described in Clause 2 of the relevant blank detail specification.

– 18 – 62319-1  IEC:2005(E)
Table 3 – Quality conformance inspection for periodic testing

Inspection  Assessment level
b
subgroup  EZ
a a a
p n c
C1A 24 5 0
C1B 24 5 0
C1 24 10 0
C2A 24 5 0
C2B 24 5 0
C3 24 10 0
C4 24 10 0
D1 24 10 0
D2 24 10 0
D3 24 10 0
a
p is the periodicity in months;
n is the sample size;
c is the permissible number of non-conforming items.
b
The content of the inspection subgroups is described in Clause 2 of the relevant blank detail
specification.
3.6 Rework and Repair
3.6.1 Rework
Rework, as defined in 4.1.4 of IECQ 001002-3, shall not be carried out if prohibited by the
relevant specification. The relevant specification shall state if there is a restriction on the
number of occasions that rework may take place on a specific component.
All rework shall be carried out prior to the formation of the inspection lot offered for inspection
to the requirements of the detail specification.
Such rework procedures shall be fully described in the relevant documentation produced by
the manufacturer and shall be carried out under the direct control of the designated
management representative (DMR). Rework shall not be subcontracted.
3.6.2 Repair
Thermistors which have been repaired as defined in IECQ 001002-3, shall not be released
under the IECQ system.
3.7 Release for delivery
Thermistors shall be released for delivery according to 3.2.6 and 4.3.2 of IECQ 001002-3,
after the Quality Conformance Inspection prescribed in the detail specification has been
carried out.
3.7.1 Release for delivery under qualification approval before the completion of
Group B tests
When the conditions of IEC 60410 for changing to reduced inspection have been satisfied for
all Group B tests, the manufacturer is permitted to release components before the completion
of such tests.
62319-1  IEC:2005(E) – 19 –
3.8 Certified test records of released lots
When certified test records are requested by a purchaser, they shall be specified in the detail
specification.
3.9 Delayed delivery
Thermistors held for a period exceeding three years (unless otherwise specified in the
relevant specification) following the release of the lot shall, before delivery, be re-examined
as specified in the relevant specification.
The re-examination procedure adopted by the manufacturer’s DMR shall by approved by the
NSI.
Once a lot has been satisfactorily re-inspected, its quality is re-assured for the specified
period.
3.10 Alternative test methods
See 3.2.3.7 of IECQ 001002-3 with the following details:
• in case of dispute, for referee and reference purposes, only the specified methods shall be
used.
3.11 Manufacture outside the geographical limits of IECQ NSIs
A manufacturer may have his approval extended to cover part or complete manufacture of
thermistors in a factory of his company located in a country which does not have a NSI for the
technical area concerned, whether this country is a IECQ member country or not, provided
that the requirements of 2.5.1.3 of IECQ 001002-3 are met.
3.12 Unchecked parameters
Only those parameters of a component which have been specified in a detail specification and
which were subject to testing shall be assumed to be within the specified limits.
It cannot be assumed that any unspecified parameter will remain unchanged from one
component to another. Should for any reason it be necessary for further parameters to be
controlled, then a new, more extensive specification shall be used.
The additional test method(s) shall be fully described and appropriate limits, sampling plans
and inspection levels specified.
4 Test and measurement procedures
This clause contains test and measurement procedures applicable to polymeric PTC
thermistors.
4.1 Standard conditions for testing
Unless otherwise specified, all tests shall be carried out under standard atmospheric
conditions for testing as specified in IEC 60068-1.
The thermistors shall attain thermal equilibrium before results are recorded.
The ambient temperature during the measurements shall be stated in the test report.

– 20 – 62319-1  IEC:2005(E)
During measurements, the thermistor shall not be exposed to draughts, direct sun rays or
other influences likely to cause error.
The total error of measurement from power dissipation, temperature tolerance and the
tolerance of the measuring equipment shall not exceed 10 % of the tolerance in the detail
specification.
The test shall be carried out in the prescribed order.
4.2 Drying and recovery
4.2.1 Drying
Where drying is called for in the specification, the thermistor shall be conditioned before
measurement is made, using Procedure 1 or Procedure 2 as called for in the detail
specification.
Procedure 1
For (24 ± 4) h in an oven at a temperature of (55 ± 2) °C and relative humidity not exceeding
20 %.
Procedure 2
For (36 ± 4) h in an oven at (100 ± 5) °C
The thermistor shall then be allowed to cool in a desiccator using a suitable desiccant such as
activated alumina or silica gel, and shall be kept therein from the time of the removal from the
oven to the beginning of the specified tests.
4.2.2 Recovery
Where recovery is required, the thermistor shall be stored at standard atmospheric conditions
for testing for 1 h to 2 h.
4.3 Visual inspection and check of dimensions
4.3.1 Visual examination
The condition, workmanship and finish shall be satisfactory as determined by visual
examination.
4.3.2 Marking
Marking shall be legible as determined by visual examination.
4.3.3 Dimensions (detail)
All dimensions prescribed in the detail specification shall be checked and they shall comply
with the values prescribed. Where applicable, measurements shall be made in accordance
with IEC 60294.
62319-1  IEC:2005(E) – 21 –
4.4 Zero-power resistance
4.4.1 The zero power resistance shall be measured at the temperature given in the detail
specification.
4.4.2 The thermistors shall be mounted by their normal means.
All measurements shall be made without self-heating of the devices (zero power condition).
The measuring method shall be such that:
a) for absolute resistance measurement, the error does not exceed 10 % of the resistance
tolerance;
b) for measurements of variation of resistance, the error does not exceed 10 % of the
specified maximum change of resistance.
The zero power resistance shall be within the limits given in the detail specification.
4.5 Insulation resistance (for insulated types only)
4.5.1 The insulation resistance of the protective coating shall be measured.
4.5.2 According to the instructions given in the detail specification one of the following test
methods is used.
Method 1
The thermistor is placed in a vessel containing metallic balls of (1,6 ± 0,2) mm diameter, so
that only the insulated parts of the thermistor are immersed (the metal of the balls shall be
such that it does not develop a resistive surface).
An electrode is placed in the metallic balls.
Method 2
A metal foil shall be wrapped closely around the body of the thermistor.
For those types not having axial terminations, a
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